{"product_id":"ignition-coil-and-iridium-spark-plugs-for-audi-s4-2005-2009-4-2l","title":"Ignition Coil and Iridium Spark Plugs for Audi S4 (2005-2009) 4.2L","description":"\u003ch2\u003eDirect-Replacement Ignition Coil and Iridium Spark Plug Kit for 2005-2009 Audi S4\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e The ignition coil and iridium spark plug kit replaces degraded factory ignition components on the 2005-2009 Audi S4 to eliminate cylinder misfires, smooth idle harmonics, and restore peak combustion efficiency.\u003c\/p\u003e\n\n\u003ch3\u003eThe Stock Audi S4 Thermal Ignition Breakdown\u003c\/h3\u003e\n\u003cp\u003eThe 40-valve \u003cstrong\u003eBHF\u003c\/strong\u003e 4.2L V8 operates with an 11.0:1 static compression ratio packed tightly within the compact \u003cstrong\u003eB7\u003c\/strong\u003e chassis engine bay. Due to restricted airflow around the aluminum cylinder heads, factory pencil coils endure continuous thermal soak. Over time, heat cycles cause the OEM potting epoxy to crystallize and micro-crack, breaking down dielectric insulation across the secondary copper windings. Concurrently, factory spark plug electrodes erode, raising gap resistance. This voltage spike forces electrical discharge to ground through fractured silicone boots, precipitating \u003cstrong\u003eP0300\u003c\/strong\u003e–\u003cstrong\u003eP0308\u003c\/strong\u003e misfires, poor catalyst performance, and unburned fuel contamination.\u003c\/p\u003e\n\n\u003ch3\u003eThe Engineering Solution\u003c\/h3\u003e\n\u003cp\u003eThis ignition kit pairs eight direct-fit coil-on-plug units with matched fine-wire iridium spark plugs designed for high thermal endurance. Each coil pack features vacuum-impregnated high-grade copper windings and thermoset epoxy potting to resist internal flashover and withstand severe underhood temperatures. Heavy-duty fluorosilicone boots prevent corona discharge and track-arcing down the plug well. The matched iridium plugs feature laser-welded 0.6mm center electrodes, dramatically reducing primary strike voltage demands, preventing spark blow-out at 7,000 RPM, and sustaining continuous flame kernel propagation.\u003c\/p\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable width=\"100%\" style=\"border-collapse: collapse; border: 1px solid #e0e0e0; font-size: 14px; margin-bottom: 20px;\"\u003e\n  \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eFitment\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e2005-2009 Audi S4\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eEngine \/ Chassis\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e4.2L V8 (BHF) \/ B7\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eStock Output\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e340 hp \/ 302 lb-ft\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eReplaces OEM Part #\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e077905115P, 077905115Q, 077905115T, 077907115K, 077905115C, 077905115E, 077905115F, 077905115H, UF418\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e2005 Audi S4 Base Sedan \/ Avant \/ Cabriolet 4.2L V8\u003c\/li\u003e\n  \u003cli\u003e2006 Audi S4 Base Sedan \/ Avant \/ Cabriolet 4.2L V8\u003c\/li\u003e\n  \u003cli\u003e2007 Audi S4 Base Sedan \/ Avant \/ Cabriolet 4.2L V8\u003c\/li\u003e\n  \u003cli\u003e2008 Audi S4 Base Sedan \/ Avant \/ Cabriolet 4.2L V8\u003c\/li\u003e\n  \u003cli\u003e2009 Audi S4 Cabriolet 4.2L V8\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this fit the B7 S4?\u003c\/strong\u003e\u003cbr\u003e Yes, this is a direct fit for the 2005-2009 Audi S4 equipped with the 4.2L V8 \u003cstrong\u003eBHF\u003c\/strong\u003e engine.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo these iridium spark plugs require manual gapping before installation?\u003c\/strong\u003e\u003cbr\u003e No, these plugs come pre-gapped to factory specifications; altering the fine iridium center wire manually can damage the brittle electrode coating.\u003c\/p\u003e\n\n\u003ch3\u003eThe Audi Precision Standard\u003c\/h3\u003e\n\u003cp\u003eCalibrated specifically to OEM secondary resistance standards, this ignition package works seamlessly with the factory Bosch Motronic ECU without triggering false diagnostic knock codes, erratic cold starts, or unwanted check engine lights.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":50594174697720,"sku":"DS-E4BFHIQ4L","price":140.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/ignition-coil-and-iridium-spark-plugs-for-audi-s4-2005-2009-4-2l-1.jpg?v=1790057741","url":"https:\/\/performancechiptuning.com\/fr\/products\/ignition-coil-and-iridium-spark-plugs-for-audi-s4-2005-2009-4-2l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}